[analyzer] Do list initialization for CXXNewExpr with initializer list arg (#127702)

Fixes #116444.

Closed #127700 because I accidentally updated it in github UI.

### Current vs expected behavior

Previously, the result of a `CXXNewExpr` was not always list initialized
when using an initializer list.

In this example:
```
struct S { int x; };
void F() {
  S *s = new S{1};
  delete s;
}
```
there would be a binding of `s` to `compoundVal{1}`, but this isn't used
during later field binding lookup. After this PR, there is instead a
binding of `s->x` to `1`. This is the cause of #116444 since the field
binding lookup returns undefined in some cases currently.

### Changes

This PR swaps around the handling of typed value regions (seems to be
the usual region type when doing non-CXX-new-expr list initialization)
and symbolic regions (the result of the CXX new expr), so that symbolic
regions also get list initialized. In the below snippet, it swaps the
order of the two conditionals.

https://github.com/llvm/llvm-project/blob/8529bd7b964cc9fafe8fece84f7bd12dacb09560/clang/lib/StaticAnalyzer/Core/RegionStore.cpp#L2426-L2448

### Followup work

This PR only makes CSA do list init for `CXXNewExpr`s. After this, I
would like to make some changes to `RegionStoreMananger::bind` in how it
handles list initialization generally.

I've added some straightforward test cases here for the `new` expr with
a list initializer. I started adding some more before realizing that the
current general (not just `new` expr) list initialization could be
changed to handle more cases like list initialization of unions and
arrays (like https://github.com/llvm/llvm-project/issues/54910). Lmk if
it is preferred to then leave these test cases out for now.